James Massola and Latika Bourke

Security experts have warned the viability of the Dutch-Australian police mission to the site of downed Malaysian Airlines flight MH17 is at risk, amid fierce fighting on the ground and a failed third attempt to reach the crash site.

Prime Minister Tony Abbott on Tuesday re-stated his determination to access the crash site, promising to hit the phones to ensure an agreement to allow investigators access is honoured and signalling a growing frustration with delays on the ground in Donetsk.

The multinational team, led by the Dutch and including Australian Federal Police, has been blocked from entering the site because of heavy fighting between Ukrainian forces and Russian-backed rebels.

Related Content

''This was a matter that was in the hands of our people on the spot. Yes, there was fighting yesterday and the day before; a few hours ago, we were optimistic that there was an agreement with the Ukrainian government and with the separatists for a humanitarian corridor to be opened for the Dutch and Australian mission to go in,'' Mr Abbott said.

He said it was high time that all three parties who had agreed to a ceasefire honoured their commitments.

He told the ABC Russia’s co-operation was vital to securing safe passage to the crash site.

''We are unlikely to get continued co-operation . . . should we be actively coming to judgment on responsibility for the plane crash,'' he said.

''Our priority is to bring home the bodies of the Australians who were killed in the plane crash.

''We have unarmed federal police trying to get to this site of the plane wreckage, they need to travel for one and a half hours, each way, each day through heavy military activity, run by Russian-backed separatists, so the risks for our people are significant and we are focused on the priorities that bring our Australians home.''

Lowy Institute military fellow James Brown said the decision to send in a police-led, military-enabled team was the right one and that, subject to permission, the unarmed team should be equipped with sidearms.

''They should have sidearms for personal safety, though it looks more like a humanitarian mission if they don't have sidearms,'' he said.

''I think it's [the mission] still worth it today, but if it gets to the point where it's been three weeks since the crash and we can't get access, at that point we need to evaluate whether it is worth doing or not.''